JP2000290081A - Spacer for hot press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spacer for a hot press which is highly thermally conductive, makes the heat transfer of the contact surface with sample powder uniform at the sintering time of hot pressing, is capable of improving the temperature distribution in a furnace and has excellent compressive strength and impact resistance. SOLUTION: This spacer consists of a C/C composite having a yarn assemblage 6 which is laminated with a required number of yarn array bodies 1 formed by nearly parallel and two-dimensionally arraying a plurality of yarn 2 consisting of carbon fibers and carbon components exclusive of the carbon fibers so as to be paralleled to the longitudinal direction of the yarn array bodies 1 adjacent to each other in a vertical direction and a matrix consisting of the carbon formed in the spacings between the carbon fibers arranged in the three-dimensional direction of the yarn assemblage 6 and the carbon fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hot press spacer used during hot press sintering.

[0002]

2. Description of the Related Art At present, a hot press sintering method is used to obtain a dense ceramic product at a relatively low temperature in a short time. In the hot press sintering method, by applying pressure to the driving force for sintering, dense sintering can be performed at a low temperature at which particle growth is suppressed. For this reason, a high-strength ceramic which is particularly excellent in mechanical strength and the like can be suitably manufactured. For example, a hot press 30 shown in FIG. 3 is used. This hot press 30
The sample powder 38 is put between the upper punch 32 and the lower punch 34 of the mold 35, and the upper push rod 31 and the lower push rod 33
And at the same time apply them all to the electric furnace 3
6 to heat. In addition, hot press 3
0 denotes a spacer 37 and a spacer 3 in the mold 35.
7 (3 pieces) with sample powder 38 between
The productivity is improved by setting and obtaining a plurality (three) of sintered bodies by one sintering.

At this time, the spacer 37 used above is used.
As the material, those made of graphite having high heat resistance and high thermal conductivity have been mainly used. However, if too much pressure is applied to the graphite spacer, the compression strength and impact resistance are not sufficient, and the graphite spacer will be damaged during hot press sintering. On the other hand, spacers other than those made of graphite (for example, special heat-resistant steel, etc.) have excellent compressive strength and impact resistance, but do not have sufficient thermal conductivity and contact with sample powder during hot press sintering. Since the heat conduction on the surface and the temperature distribution in the furnace are also non-uniform, there is a problem that productivity and quality are deteriorated particularly when a large ceramic product is sintered.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such problems of the related art,
Its purpose is to have high thermal conductivity, uniform heat conduction on the contact surface with the sample powder during hot press sintering, improve the temperature distribution in the furnace, compressive strength and impact resistance It is intended to provide a hot press spacer having excellent heat resistance.

[0005]

That is, according to the present invention, a yarn formed by arranging at least a plurality of yarns composed of carbon fibers and carbon components other than carbon fibers in a two-dimensional manner substantially in parallel. An array, a yarn aggregate formed by laminating the required number so as to be parallel to the longitudinal direction of the vertically adjacent yarn array, and carbon fibers and carbon fibers arranged in the three-dimensional direction of the yarn aggregate A spacer for hot pressing, comprising a C / C composite having a matrix of carbon formed in gaps.

At this time, in the present invention, the carbon fibers are preferably pitch-based carbon fibers, and the thermal conductivity in the direction parallel to the longitudinal direction of the C / C composite yarn is 400 W / m · K or more. It is preferred that

Further, in the present invention, the ratio of the thermal conductivity in the direction parallel to the longitudinal direction of the yarn of the C / C composite to the thermal conductivity in the yarn laminating direction is preferably at least 5: 1 or more. .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The main feature of the hot press spacer of the present invention is that it is formed of a C / C composite having heat conduction anisotropy. Thereby, the spacer can have a thermal conductivity of 400 W / m · K or more (preferably, 600 W / m · K or more), and the thermal conductivity of the contact surface with the sample powder at the time of hot press sintering. It is possible to improve the temperature distribution in the furnace and to improve the compressive strength and impact resistance, so that the productivity and quality can be improved especially when sintering large ceramic products. it can.

Here, the C / C composite used in the present invention will be described in more detail. C / used in the present invention
The C composite is a material in which a matrix of carbon is formed in a gap between carbon fibers arranged in a three-dimensional direction, and as shown in FIGS.
A, 1B, 1C, 1D, 1E, 1F are vertically stacked, and each yarn array 1 has two yarns two-dimensionally arranged, and only the longitudinal direction of each yarn 2 is parallel. In addition, the longitudinal direction of each yarn 2 in each of the yarn arrays 1 vertically adjacent to each other is also parallel.

Here, the C / C composite has a thermal conductivity of 400 W / in a direction parallel to the longitudinal direction of the yarn 2.
It is important that the ratio between the thermal conductivity in the direction parallel to the longitudinal direction of the yarn 2 and the thermal conductivity in the laminating direction of the yarn 2 is at least 5: 1 or more. Thus, the C / C composite is
By forming the flat part of the product so as to have the heat conduction anisotropy and to make the length direction of the yarn of the C / C composite parallel, the heat conduction of the flat part can be made uniform. In addition, since the thermal conductivity can be improved, the temperature in the furnace during hot press sintering can be improved.

The C / C composite is rich in toughness, has excellent impact resistance, high hardness and high heat dissipation, and is lightweight.

The carbon fiber used in the C / C composite is preferably a pitch-based carbon fiber obtained by preparing a spinning pitch, melt-spinning, infusible, and carbonized using petroleum pitch or coal tar pitch as a raw material. . This is because the thermal conductivity can be increased (about 5 times) as compared with the PAN-based carbon fiber. Also,
When the preformed body made from the pitch-based carbon fiber is fired to produce the C / C composite used in the present invention, setting the firing temperature to 2400 ° C. or higher involves graphitizing the entire matrix and heat conduction. This is preferable because the rate can be increased.

Further, the C / C composite contains 20 to 70% of carbon fibers, and the balance is at least one selected from the group consisting of boron nitride, boron, copper, bismuth, titanium, chromium, tungsten, and molybdenum. It may contain a substance. This is because these substances have lubricity, so that the lubricity of the fiber can be maintained and a decrease in toughness can be prevented. For example, the content of boron nitride is 100% by weight of a base material composed of a C / C composite.
Is preferably 0.1 to 40% by weight.
If the amount is less than 0.1% by weight, the effect of imparting lubricity by boron nitride cannot be sufficiently obtained. If the amount exceeds 40% by weight, the brittleness of boron nitride also appears in the C / C composite.

Here, the C / C composite is usually formed by bundling hundreds to tens of thousands of carbon fibers having a diameter of about 10 μm to form a fiber bundle (yarn), and then forming the fiber bundle with a thermoplastic resin. A flexible thread-like intermediate material prepared by coating is obtained, and is formed into a sheet by the method described in JP-A-2-80639. The sheet is arranged in a two-dimensional or three-dimensional direction. One-way sheet (UD sheet)
Or by laminating the above sheets to form a preformed body (fiber preform) of a predetermined shape, such as a thermoplastic resin made of an organic substance formed on the outer periphery of the fiber bundle of the preformed body. What is necessary is just to bake the coating and remove the above-mentioned coating from carbonization. In the C / C composite, the carbon component other than the carbon fibers in the yarn is preferably a carbon powder, particularly preferably a graphitized carbon powder.

Next, the C / C composite used in the present invention can be preferably produced by the following method. That is, it acts as a matrix on the bundle of carbon fibers, and eventually contains a powdery binder that becomes free carbon with respect to the bundle of carbon fibers, for example, pitch and coke.
Further, a carbon fiber bundle is produced by adding a phenol resin powder or the like as necessary. As described in JP-A-2-80639, a flexible film made of a plastic such as a thermoplastic resin is formed around the carbon fiber bundle to obtain a preformed yarn as a flexible intermediate material. The foamed yarn is formed into a sheet-shaped prepreg sheet, and the required amount is laminated as shown in FIGS. 1 and 2.
A preform is obtained by molding under the condition of cm ² . Alternatively, the pre-formed body may be formed,
Carbonized at 1200 ° C and graphitized at 2400 ° C or higher,
A fired C / C composite is produced.

As the carbon fiber, a pitch-based carbon fiber obtained by using a petroleum pitch or coal tar pitch as a raw material, preparing a spinning pitch, melt-spinning, infusing, and carbonizing is used. Thermosetting resins such as phenolic resins and epoxy resins and tars and pitches are used as carbon precursors necessary for forming the matrix, and these include cokes, metals, metal compounds, inorganic and organic compounds, and the like. You may go out.

When manufacturing the hot press spacer of the present invention, the C / C composite manufactured as described above may be manufactured by cutting the C / C composite to an appropriate size using a surface grinder or the like and polishing and finishing. Good.

[0018]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. (Example) A prepreg sheet impregnated with a phenol resin was laminated on carbon fibers unidirectionally aligned in one direction as shown in FIG. 1, and was hot-pressed at 180 ° C. and 10 kg / cm.
^The resin was cured in ² . Next, the mixture was fired at 2400 ° C. in nitrogen to produce a C / C composite.
At this time, the density of the obtained C / C composite was 1.9.
g / cm ³ , open porosity was 10%, thermal conductivity in a direction parallel to the longitudinal direction of the yarn was 400 W / m · K, and thermal conductivity in the laminating direction of the yarn was 80 W / m · K. .

After cutting the plate material made of the C / C composite manufactured as described above using a surface grinder, the flatness is 0.1 mm or less and the flatness [Rmax] is 10 μm or less with an 800 # grindstone. By polishing so as to obtain, the circular member 37a shown in FIG.
(Radius: 100mm, Angle: 45 °, Thickness: 20mm)
Was prepared. The circular member 37a is manufactured so that the longitudinal direction of the yarn 2 of the C / C composite is as parallel as possible in the radial direction, and the thermal conductivity in the plane portion of the circular member 37a is 400W. / M · K. Next, by combining the eight obtained circular members 37a, a spacer 37 for hot press (diameter: 200 mm, thickness: 20 mm) as shown in FIG.
I got

Next, the productivity and yield of ceramic products when the obtained hot press spacer was applied to the hot press shown in FIG. 3 were examined.
As a result, the obtained hot-press spacer (Example) has high thermal conductivity, can make uniform the heat conduction of the contact surface with the sample powder at the time of hot-press sintering, and has the compressive strength and resistance to heat. Because it has excellent impact resistance,
Compared with conventional hot press spacers, the productivity and quality of large ceramic products were greatly improved.

[0021]

As is apparent from the above description, the hot press spacer of the present invention has high thermal conductivity,
The heat conduction of the contact surface with the sample powder during hot press sintering can be made uniform, the temperature distribution in the furnace can be improved, and the compression strength and impact resistance are also excellent.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an example of a yarn aggregate used in the present invention.

FIG. 2 is a perspective view schematically showing another example of the yarn aggregate used in the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a hot press.

FIG. 4 shows an example of a hot press spacer produced in the example, where (a) is a perspective view,
(B) is a perspective view showing a circular member constituting the spacer.

[Explanation of symbols]

1A, 1B, 1C, 1D, 1E, 1F...
2 ... Yarn (fiber bundle), 6 ... Yarn assembly, 30 ... Hot press, 31 ... Top push rod, 32 ... Top punch, 33
... lower push rod, 34 ... lower punch, 35 ... molding die, 36
... Electric furnace, 37 ... Spacer, 37a ... Circular shaped member, 3
8 ... Sample powder.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AA37A AA37B AK33 BA02 BA03 BA04 BA05 BA14 DG01A DG01B DG06A DG06B DH01A DH01B EJ08 GB51 GB90 JJ01 JJ01A JJ01B JK05 JK10 YY00A YY00B

Claims (4)

[Claims] 1. A yarn array formed by arranging at least a plurality of yarns composed of carbon fibers and carbon components other than carbon fibers in a two-dimensional manner substantially in parallel to each other, the yarn arrays being vertically adjacent to each other. A yarn aggregate formed by laminating the required number of layers so as to be parallel to the longitudinal direction of the yarn aggregate, and a matrix made of carbon formed in a gap between the carbon fibers and the carbon fibers arranged in the three-dimensional direction of the yarn aggregate. A hot press spacer comprising a C / C composite. 2. The hot press spacer according to claim 1, wherein the carbon fibers are pitch-based carbon fibers. 3. The thermal conductivity of the C / C composite in a direction parallel to the longitudinal direction of the yarn is 400 W / m ·
The hot press spacer according to claim 1, which has a K or more. 4. The C / C composite according to claim 1, wherein a ratio of a thermal conductivity in a direction parallel to a longitudinal direction of the yarn to a thermal conductivity in a yarn laminating direction is at least 5: 1 or more. The hot press spacer according to any one of the preceding claims.